Line dispensing device with eddy current braking for use with climbing and evacuation

ABSTRACT

This disclosure describes embodiments of novel line dispensing devices and methods for dispensing and retracting a line of a line dispensing device.

RELATED APPLICATIONS

This application is a continuation application of and claims the benefitof priority from U.S. patent application Ser. No. 12/858,839, filed onAug. 18, 2010, now U.S. Pat. No. 8,490,751; which is acontinuation-in-part application of PCT/NZ2010/000011 filed on Jan. 29,2010, which claims priority to New Zealand Application No. 575464, filedon Mar. 12, 2009, the entire disclosures of all of which are herebyincorporated herein by reference.

INTRODUCTION

Line dispensing devices, such as auto-belay devices used for climbing,are used to protect against falls by retracting slack when the line isnot under load and providing a braking force when the line is loaded, sothat the weight on the end of the line is lowered at a safe speed.Several braking systems, such as a friction-brake or hydraulic dampeningmechanism, have been utilized in line dispensing devices. These devicestypically utilize a clutch to engage and disengage the braking system sothat the braking system is completely disengaged from the rest of thedevice when the line is not under load. While the clutch is an effectivemechanism for selectively engaging a braking system, prolonged use ofthe clutch will wear on the mechanism over time until the clutch is nolonger safe and/or effective. Because failure of a clutch often resultsin the braking system becoming completely disengaged from the rest ofthe device, clutch failure in line dispensing devices can lead to injuryof a user. For example, MSA recently recalled all of their line ofRedpoint Decenders due to injury reported to have been caused by clutchfailures. Accordingly, line dispensing devices with clutchless brakingsystems having no or minimal risk of mechanical failure are desirable.This is particularly true when the line dispensing device is a safetydevice.

SUMMARY

This disclosure describes embodiments of novel line dispensing devicesand methods for dispensing and retracting a line of a line dispensingdevice.

In part, this disclosure describes a line dispensing device. The linedispensing device includes the following elements:

a) a shaft;

b) a rotor, the rotor comprising at least one pivotable member, whereinthe rotor is rotatable around the shaft;

c) at least one magnet configured to apply a magnetic field extending atleast partially orthogonal to a plane of rotation of the pivotablemember;

d) a cradle, the cradle rotatable around the shaft and configured tohold the at least one magnet;

e) a coupling transmission, the coupling transmission coupling the rotorto the cradle and the at least one magnet;

f) a line, the line coupled to the cradle;

g) a retracting mechanism, the retracting mechanism is operativelycoupled to the cradle and attached to the shaft at one end of theretracting mechanism; and

h) a housing, the housing containing at least a portion of the shaft,the rotor, the at least one pivotable member, the at least one magnet,the cradle, the coupling transmission, the retracting mechanism, and theline.

Another aspect of this disclosure describes a line dispensing device.The line dispensing device includes the following elements:

a) a shaft;

b) a cradle, the cradle rotatable around the shaft;

c) at least one magnet configured to apply a magnetic field extending atleast partially orthogonal to a plane of rotation of the cradle;

d) a rotor, the rotor comprising at least one pivotable member, whereinthe rotor is rotatable around the shaft and configured to hold the atleast one magnet;

e) a coupling transmission, the coupling transmission coupling the rotorand the at least one magnet to the cradle;

f) a line, the line coupled to the cradle;

g) a retracting mechanism, the retracting mechanism is operativelycoupled to the cradle and attached to the shaft at one end of theretracting mechanism; and

h) a housing, the housing containing at least a portion of the shaft,the rotor, the at least one pivotable member, the at least one magnet,the cradle, the coupling transmission, the retracting mechanism, and theline.

Yet another aspect of this disclosure describes a method forautomatically feeding and retracting line. The method includesperforming the following steps: providing a line for extension andretraction; applying a retraction force to the line with a retractingmechanism; and applying a braking force to the line that provides asubstantially constant speed for extension over a range of appliedtorques by balancing an increase in an applied torque with an equal andopposite increase in a braking torque arising from an inducededdy-current from at least one conductive member intersecting a largerportion of a magnetic field.

These and various other features as well as advantages whichcharacterize the systems and methods described herein will be apparentfrom a reading of the following detailed description and a review of theassociated drawings. Additional features are set forth in thedescription which follows, and in part will be apparent from thedescription, or may be learned by practice of the technology. Thebenefits and features of the technology will be realized and attained bythe structure particularly pointed out in the written description andclaims hereof as well as the appended drawings.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory and areintended to provide further explanation of the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The following drawing figures, which form a part of this application,are illustrative of embodiment systems and methods described below andare not meant to limit the scope of the disclosure in any manner, whichscope shall be based on the claims appended hereto.

FIG. 1 illustrates an embodiment of an exploded view of a linedispensing device.

FIG. 2 illustrates an embodiment of a side view of a line dispensingdevice.

FIG. 3 illustrates an embodiment of a front cross-sectional view of aline dispensing device.

FIG. 4 illustrates an embodiment of a front view of a line dispensingdevice.

FIG. 5 illustrates an embodiment of an isometric partial cross-sectionalview of a line dispensing device.

FIG. 6 illustrates an embodiment of a side cross-sectional view of aline dispensing device.

FIG. 7 illustrates an embodiment of an isometric view of a configurationof a cradle, magnet arrangement, a retraction mechanism drum, and a lineof a line dispensing device.

FIG. 8 illustrates an embodiment of a front cross-sectional view of aconfiguration of a cradle, magnet arrangement, and retraction mechanismdrum of a line dispensing device.

FIG. 9 illustrates an embodiment of an isometric view of a rotor for aline dispensing device.

FIG. 10 illustrates an embodiment of a side view of a rotor for a linedispensing device.

FIG. 11 illustrates an embodiment of an isometric view of a couplingtransmission for a line dispensing device.

FIG. 12 illustrates an embodiment of a cross-sectional view of acoupling transmission for a line dispensing device.

FIG. 13 illustrates an embodiment of a side view of the retractionmechanism for a line dispensing device.

FIG. 14 illustrates an embodiment of a method for dispensing andretracting a line of a line dispensing device.

FIG. 15 illustrates and embodiment of a plot of Torque vs. Speed for anexemplary prior art eddy-current braking mechanism.

FIG. 16 a illustrates and embodiment of a partial schematic plan diagramof an eddy current braking mechanism, the rotor moving in response to aninitial braking torque and a force diagram of the eddy-current brakingmechanism.

FIG. 16 b illustrates and embodiment of a partial schematic plan diagramof the eddy current braking mechanism of FIG. 16 a with the rotorrotating under an intermediate braking torque and a force diagram of theeddy-current braking mechanism.

FIG. 16 c illustrates and embodiment of a schematic plan diagram of theeddy current braking mechanism of FIGS. 16 a and 16 b with the rotorrotating under a maximum braking torque and a force diagram of theeddy-current braking mechanism.

FIG. 17 illustrates and embodiment of a schematic side elevation of partof the eddy current braking mechanism of FIGS. 16 a-16 c.

FIG. 18 illustrates and embodiment of a plot of Torque vs. Speed of therotor used with the braking mechanism of FIGS. 16 a-16 c.

FIG. 19 illustrates and embodiment of a plot of Speed vs. Torque of therotor used with the braking mechanism of FIGS. 16 a-16 c.

DETAILED DESCRIPTION

This disclosure describes embodiments of novel line dispensing devicesand methods for dispensing and retracting a line of a line dispensingdevice.

In one embodiment an eddy-current braking mechanism includes a rotor,rotatable about a rotor axis; at least one electrically conductivemember coupled to the rotor for rotation therewith; at least one magnetconfigured to apply a magnetic field extending at least partiallyorthogonal to the plane of rotation of the conductive member; andcharacterized in that upon rotation of the rotor, the conductive memberis configured to move at least partially radially from the rotor axisinto the applied magnetic field.

In general, movement of the conductive member through the appliedmagnetic field induces an eddy-current in the conductive member when theconductive member intersects the magnetic field.

To aid clarity and avoid prolixity, reference herein will be made to theconductive member being coupled to the rotor. However, it will beappreciated that a “reverse configuration” is also possible and withinthe scope of the disclosure. This “reverse configuration” may have themagnet coupled to the rotor and configured to move toward a conductivemember such that the conductive member will intersect the magneticfield.

To aid clarity and to avoid prolixity the braking mechanism will bedescribed herein for an auto-belay. However, it should be appreciatedthat the braking mechanism may be used in other rotary braking orretarding applications and thus reference herein to an auto-belay isexemplary only and should not be seen to be limiting.

It will also be appreciated that the braking mechanism may also be usedin linear braking applications by coupling the rotor to a linear device(e.g. by a cam or chain drive mechanism).

Reference herein to “radial” movement of the conductive member should beunderstood to include any movement with a component in a directiontoward or away from the axis of rotation of the rotor and/or conductivemember and should be interpreted to include both linear and non-linearradial movement.

Reference herein to “outward” radial movement refers to movement in adirection away from the axis of rotation and similarly “inward” refersto a direction toward the axis of rotation.

Reference herein to the conductive member being “coupled” to the rotorshould be understood to mean any direct or indirect connection such thatthe conductive member rotates with the rotor. It should also beappreciated that connection need not be mechanical.

The magnetic field applied by the magnet will herein be referred to asthe “applied” magnetic field and the magnetic field(s) generated byeddy-currents in the conductive member are referred to as “reactive”magnetic field(s).

In some embodiments the eddy-current induced in the conductive membergenerates a reactive magnetic field opposing the applied magnetic field.The reactive force generated by the opposing ‘applied’ and ‘reactive’magnetic fields is thus transferred to the conductive member to opposemovement thereof. As the conductive members are coupled to the rotor,the rotation of the rotor is also opposed by the reactive force.

As used herein, the terms “brake” or “braking” respectively refer to anyapparatus or process for applying a force opposing movement of anobject.

As used herein, the term “rotor” refers to any rotatable element and mayinclude a driveshaft, axle, gear, screw, disc, wheel, cog, combinationthereof or any other rotatable member.

As used herein, the term “conductive member” refers to any electricallyconductive, preferably non-ferrous member.

As used herein, the term “magnet” refers to any magnet or device capableof generating a magnetic field and may include electromagnets,“permanent” magnets, “temporary” magnets, magnetized ferromagneticmaterials, or any combination thereof.

The conductive member may be configured to move at least partiallyradially from the rotor axis into the magnetic field.

The conductive member may rotate with the rotor about the rotor axis.

It should be appreciated that the conductive member need not be directlyconnected to the rotor and could instead be connected via intermediategears or other couplings. In such embodiments, the gear or couplingattached to the conductive member can be considered the “rotor” or partthereof.

It should also be appreciated that in such embodiments where theconductive member is indirectly coupled to the rotor, the conductivemember may rotate about another axis parallel or non-parallel to therotor axis.

In a further embodiment, the rotor may be coupled to a shaft or the likevia an overdrive, or underdrive, gear transmission arrangement, suchthat the rotor rotates at a different speed to that of the shaft.

In one embodiment, the rotor is coupled to a spool of line andconfigured for rotation therewith. Thus, the rate of line dispensing, orretracting, from the spool can be controlled by controlling the speed ofrotation of the rotor with the braking mechanism.

In an embodiment, the braking mechanism includes a plurality ofelectrically conductive members (henceforth referred to simply asconductive members).

The braking effect may be increased by increasing the number ofconductive members moving through the applied magnetic field. However,the number and size of the conductive members will be limited by thesize and weight constraints of the application. Thus, for example, inauto-belay applications, preferably three said conductive members areprovided.

In an embodiment, the conductive member is pivotally attached to therotor and configured to pivot about a pivot axis to move at leastpartially radially into the applied magnetic field upon rotation of therotor.

In one embodiment, the conductive member is pivotally attached to therotor at a point eccentric to the rotor axis.

The conductive member may have a center of mass (or mass centroid)eccentric to the pivot and rotor axes. The conductive member will thuspivot as a result of torque applied to the conductive member by therotor via the pivot connection and by centrifugal effects acting on theconductive member which are centered at the center of mass. The strengthof centrifugal effect is dependant on the rotor speed, thus theconductive member will move radially at a rate dependant on the rotorspeed.

In another embodiment, the center of mass (or mass centroid) may belocated at the pivot axis. For example, the conductive member may beshaped with a counter balance arrangement with an even mass distributionabout the pivot axis. Such an embodiment provides a transfer of radialforce directly about the pivot axis and as such does not apply amovement to the arm about the pivot axis. Therefore the braked responsein this embodiment is independent of the radial force acting on the armmass.

It should be appreciated that the conductive member may be of any shapesuitable for the application. The shape of the conductive memberdetermines the area of magnetic field intersected by the conductivemember when moving radially into the magnetic field, the eddy-currentsand reactive magnetic field generated, and therefore the correspondingbraking torque. The shape of the conductive member may be modified tomodify the braking torque characteristics required for an application.

In an embodiment, one end of a biasing device, such as a spring or otherbiasing device/mechanism, is attached to the conductive member at apoint distal to the pivot axis and the other end to the rotor at aposition to provide a bias opposing the radial movement of theconductive member resulting from rotor rotation. Calibration of thebiasing device thus provides a means for controlling the amount ofradial movement of the conductive member relative to angular velocityand therefore the area of conductive member intersecting the appliedmagnetic field at any particular angular velocity. The braking forceapplied to the conductive member during movement through the appliedmagnetic field may also be applied to the rotor via the biasing deviceand/or through the attachment of the conductive member to the rotor.

In one embodiment, the biasing device includes a calibration mechanismcapable of selectively increasing and/or decreasing the level of biasingdevice bias applied. Such a calibration mechanism may, for example, beprovided by a tensioning screw that is capable of reversiblycontracting/extending a spring to thus adjust the biasing device biasapplied. Such a tensioning screw may prove useful in calibrating thebraking mechanism quickly and easily without requiring disassembling toadjust or replace the biasing device. In auto-belay applications suchquick calibration may prove important where it is necessary to changethe maximum rotation speed required.

It will be appreciated that the biasing device may be configured to biasthe conductive member toward or away from the applied magnetic fielddepending on the requirements of the respective application. Forexample, in applications requiring increasing braking torque to counterincreasing applied torque (to prevent acceleration), the biasing devicepreferably biases the conductive member radially out of the appliedmagnetic field.

In an alternative embodiment, (for applications requiring a decreasingrate of braking torque with respect to speed) the biasing device may beattached to the conductive member and to the rotor to provide a bias tothe conductive member to move the conductive member radially into theapplied magnetic field. The conductive member may be configured to moveradially inward on rotation, e.g. by providing a counterweight orpositioning the mass centroid on an opposing side of the pivot axis tothe biasing device attachment. Such an embodiment may be achieved, forexample, by providing a conductive member on one end of a leverpivotable about an intermediate point, the other lever end having acounterweight configured to move outwardly under centrifugal effectswhen the rotor rotates. The conductive member, or alternatively thecounterweight, may be attached to the rotor via a biasing device to biasthe conductive member towards the applied magnetic field. Therefore, asthe rotor rotates, the lever will pivot the conductive member away fromthe magnetic field against the bias and braking torque applied to theconductive member.

In one embodiment, the biasing device is attached to the rotor at aposition spaced from the eccentric pivot axis in the direction ofrotation to be braked.

In an alternative embodiment, the biasing device may be provided as atorsion spring or similar attached at one end to the rotor and at theother end to the conductive member about the pivot axis, the torsionspring configured to oppose pivoting of the conductive member toward oraway (depending on the application) from the magnetic field.

The aforementioned spring configurations constrain the pivoting range ofthe conductive member between the maximum and minimum spring extension,preferably with, respectively, the maximum and minimum area ofconductive member intersecting the applied magnetic field.

The pivoting range is also preferably constrained to one side of thepivot axis to ensure that the braking torque is only applied in onerotation direction and not the opposing direction. Such a‘unidirectional’ configuration is useful in auto-belay applicationswhere it is undesirable to have a braking effect on the line whenascending, as this will oppose the line retraction mechanism andpotentially create slack in the line.

The rate at which the conductive member moves toward the magnetic fieldis dependant on the applied torque, spring bias and the reactionarycentrifugal force acting on the conductive member, i.e. the conductivemember will move toward the magnetic field if the component of appliedtorque and centrifugal force (dependant on rotation speed and conductivemember mass) opposing the spring bias is greater than the spring bias.As the spring extends, the “spring” bias or restoring force F_(s)increases approximately according to F_(s)=kx where k is the springconstant and x is the extension from equilibrium. Once the conductivemember is in the magnetic field; the eddy-current reactive force will beadded to the pivoting caused by the applied torque and centrifugalforce, the spring bias thus opposes all three forces and the spring willtherefore extend until the restoring force equals the torque applied tothe conductive member about the pivot axis.

In an embodiment, the braking mechanism includes a plurality ofpermanent magnets arranged in a generally circular or arcuate magnetarray, concentric with the rotor.

In an alternative embodiment, the braking mechanism may include aplurality of permanent magnets arranged in a linear array, for example,in a square or triangular array with the rotor axis generally in thecenter thereof.

In one embodiment, two said arrays are provided on opposing sides of theplane of rotation of the conductive member, the magnets of each arrayhaving opposite poles substantially opposing each other. A magneticfield is thus created that extends between the opposing poles (Northopposing South) of opposing magnets, preferably, in a directionsubstantially perpendicular to the plane of rotation of the conductivemember.

In an alternative embodiment, one array may be provided on one side ofthe rotor and a steel or ferromagnetic plate located on the other side.However, it will be appreciated that such a “one-sided” magnetic arraymay provide a weaker magnetic field than a comparative two-sided array.

In a further embodiment, the magnet array provided on one or both sidesof the conductive member may be arranged in a Halbach, or similarconfiguration to focus the magnetic field in the direction of theconductive member.

In an embodiment, the magnet array is provided with a steel or otherferromagnetic backing attached to a surface of the magnets on an“outer”, opposing side to the conductive member.

In yet another embodiment, the magnet may be provided as a single magnetshaped to encircle the rotor and conductive member, such that radialmovement of the conductive member will result in the conductive memberintersecting the applied magnetic field.

It will be appreciated that in order for an eddy-current effect to begenerated, the conductive member must intersect and move relative to themagnetic field. By way of example, this may be achieved by:

a) fixing the magnet in position and rotating the rotor and conductivemember such that the conductive member intersects and moves through themagnetic field and vice versa; or

b) rotating both the conductive member and the magnet, but at differingangular velocity, e.g. the rotor and conductive member may be configuredto rotate in the same direction as the magnet but at a greater angularvelocity, or alternatively, the magnet may be configured to rotate inthe opposite direction to that of the conductive member.

Thus, in one embodiment, the magnet is fixed in position such that itdoes not rotate with the rotor, the rotor and conductive membersrotatable relative to the magnet such that the conductive memberintersects and moves through the magnetic field. It should beappreciated that the term “fixed” as used in this embodiment refers to amagnet being static relative to the rotor, e.g. similar to a motorstator. Thus, the term “fixed” should not be interpreted to mean themagnet is fixed in position relative to any housing, superstructure orother objects.

In an embodiment, the magnet is configured to rotate upon rotation ofthe rotor at a different angular velocity to that of the rotor.

Rotation of the magnet(s) relative to the rotor as the rotor is rotatingprovides a mechanism for varying the relative angular velocity and hencethe strength of the braking torque. The magnet(s) may be rotated in thesame direction as the rotor to reduce the braking torque or in theopposite direction to increase it.

In an another embodiment, the magnet is coupled to the rotor forrotation therewith in a substantially opposing direction to that of therotor.

In a further embodiment, the rotor is coupled to the magnet via acoupling transmission.

In this embodiment, a coupling transmission may be used to alter therelative angular velocity of the rotor (and conductive member) relativeto the magnet, where the applied torque drives a cradle connected to themagnets and coupled to the rotor via a coupling transmission. Inalternate embodiments, the arrangement may be the other way round.

Reference to a coupling transmission throughout this specificationshould be understood to refer to a mechanism used to transmit powerbetween two articles to which it is coupled. A coupling transmission maybe a mechanical or fluid gear transmission, or a chain drive or frictioncoupling, or by any other such transmission as are well known to thoseskilled in the art.

For example, a gear transmission may be configured to rotate themagnet(s) in the opposing direction to that of the rotor, therebypotentially multiplying the relative velocity between the conductivemember and magnet.

This braking mechanism may thus achieve an increased braking effect byincreasing the relative speed between the conductive member and magnet,without a significant increase in materials or size.

In other embodiments the rotor is coupled to the magnet by a variety ofmeans, including by a chain drive or a friction coupling.

In a further embodiment, a stop may be provided for limiting the rangeof radial movement of the conductive member.

Preferably, the stop is positioned to limit the radial movement of theconductive member to a position of maximum magnetic field intercepted.

Such a stop can be utilized to transfer the braking force applied to theconductive member to the rotor by effectively “fixing” the conductivemember with respect to the rotor while the conductive member is in themagnetic field.

Furthermore, provision of such a stop provides a “safety” feature toensure that if the biasing device breaks, detaches or otherwise fails,the conductive member will still apply a braking torque (preferablymaximum) to the rotor. Without such a stop, the conductive member maymove out of the magnetic field and no longer apply a braking torque.

In an alternative embodiment, the stop may be provided as part of abiased ratchet mechanism, the conductive member moving against the biasto progressive radial positions and thus progressive levels of brakingtorque.

In one embodiment, an eddy-current braking mechanism includes: a rotor,rotatable about a rotor axis: at least one electrically conductivemember coupled to the rotor for rotation therewith; at least one magnetconfigured to apply a magnetic field extending at least partiallyorthogonal to the conductive member; and characterized in that uponrotation of the rotor, the conductive member is configured to moveradially outward from the rotor axis into the applied magnetic field,movement of the conductive member through the applied magnetic fieldthereby inducing an eddy-current in the conductive member when theconductive member intersects the magnetic field.

In an embodiment, the magnetic field primarily extends substantiallyorthogonally to the plane of rotation of the conductive member.

In another embodiment, a plurality of magnets and conductive members areprovided, each conductive member capable of reversible movement into amagnetic field applied by one or more of the magnets.

In yet another embodiment, the conductive member is configured to movewith respect to the rotor along a radial track from the rotor axis inresponse to rotation of the rotor.

In one embodiment, the conductive member is configured to move into themagnetic field as a result of radial acceleration applied by the coupledrotor, the conductive member thus moving radially outward with respectto the rotor.

In a further embodiment, a biasing device, such as a spring orequivalent biasing device/mechanism is attached to the conductive memberand to the rotor to provide a bias opposing the outward radial movementof the conductive member. Calibration of the biasing device thusprovides a means for controlling the rate of radial movement of theconductive member and therefore the area of conductive memberintersecting the magnetic field.

This “linear” embodiment thus provides a braking mechanism that worksindependent of the direction of rotation of the rotor.

The configuration of the braking torque applied to both the “linear” and“pivoting” (i.e. with pivoting conductive member) embodiments can bemodified and calibrated by changing the level of bias thereby providingan effective means of accommodating applications requiring specificbraking torque profiles.

Existing auto-belay systems typically use a friction-brake or hydraulicdampening mechanism to control the descent rate. Friction-brakes clearlyhave disadvantages compared with eddy-current brakes as the frictionalcontact involves substantial heat generation, wear and correspondingsafety problems. Hydraulic dampening mechanisms are expensive andvulnerable to leaks, pressure and calibration problems.

An ideal auto-belay system would provide a constant or controllabledescent rate with minimal friction and corresponding wear while alsoproviding sufficient braking force in a small compact device.

The prior art is replete with various eddy-current braking systems.However, none of the prior art systems appear suitable for applicationin an auto-belay or other applications where a constant speed ofrotation is required where the torque applied may vary. Thischaracteristic of prior art systems is illustrated in FIG. 14 whichshows an approximate plot of braking torque against rotation speed for atypical disc-type eddy-current braking system.

An eddy-current braking mechanism as described herein may be configuredsuch that the speed of rotation of the rotor is constant over a range ofapplied torques (the “operating range”), the applied torque being theforce applied to the rotor causing it to rotate. This constant speed ofrotation may arise due to any increase in the applied torque (in theoperating range) being balanced by an equal and opposite increase in thebraking torque arising from the induced eddy current as the conductorintersects more of the magnet field.

Thus, when the rotor initially begins to rotate, the speed of rotationof the eddy-current braking mechanism increases substantially linearlywith the applied torque. This situation continues until the electricalconductor, which is coupled to the rotor to rotate with it, enters theapplied magnetic field of the magnet. Movement of the conductor throughthe magnetic field induces eddy currents in the conductor which opposethe motion through the magnetic field, thus providing a braking force onthe motion of the conductor. The magnitude of the braking force dependson a number of factors, including the degree to which the conductorintersects the magnetic field and the strength of the field.

In an eddy-current braking mechanism as described herein the strength ofthe magnetic field, configuration of the conductor, and the biasingmechanism, may all be chosen such that an increase in torque applied tothe rotor is balanced by an equal and opposite increase in brakingtorque throughout the required operating range of torque, at a constantspeed of rotation of the rotor throughout the operating range.

At some applied torque the conductor may intersect the maximum area ofmagnetic field available under the particular embodiment of the brakingmechanism. At this torque the braking force is also at a maximum.Therefore, as the applied torque is increased further, the speed ofrotation will again become substantially linear with respect to theincrease in applied torque.

In one embodiment, a line dispensing device includes: a brakingmechanism substantially as hereinbefore described, and a spool of linecoupled to the rotor and/or conductive member for rotation therewith.

In an embodiment, the line dispensing device is an auto-belay.

In another embodiment, the rotor and/or spool includes a biasedretracting mechanism for opposing extension of line from the spool, theretracting mechanism configured to retract the line when tension appliedto the line falls below a predetermined level.

As used herein, the term “line” refers to any cable, rope, string,chain, wire, webbing, strap or any other length of flexible material.

In an embodiment, a method of braking rotation of an object includes thesteps of: coupling a conductive member to the object for rotationtherewith; providing at least one magnet configured to apply a magneticfield extending at least partially into the plane of rotation of therotatable conductive member; and configuring the conductive member tomove into the magnetic field upon rotation of the object.

In one embodiment, the method of braking rotation of an objectsubstantially as hereinbefore described, includes the further step ofrotating the object to thus move the conductive member into the magneticfield; the magnetic field thereby inducing an eddy-current in theconductive member.

The braking mechanism as described herein provides significantadvantages over the prior art by providing an eddy-current brakingmechanism capable of one or more of:

-   -   limiting the speed to a constant level over a range of applied        torques;    -   applying sufficient braking torque using a compact apparatus;        and    -   providing an eddy-current brake for use with        auto-descenders/auto-belays.        Further, the braking mechanism as described herein provides        significant advantages over the prior art by providing an        eddy-current braking mechanism that does not require the use of        a clutch.

It will be appreciated that the braking mechanism as described hereinmay therefore find particular use for speed control and/or braking innumerous applications, such as, by way of example, speed control of:

-   -   a rotor in wind, hydro, and other rotary turbines;    -   exercise equipment, e.g. rowing machines, epi-cyclic trainers;    -   roller-coasters and other amusement rides;    -   elevator and escalator systems;    -   evacuation descenders and fire-escape devices;    -   conveyor systems;    -   rotary drives in factory production facilities;    -   materials handling devices such as conveyor belts or a braking        device in a chute for example, or to control the descent rate of        an item down a slide;    -   dynamic display signage, e.g. in controlling the rotation speed        of rotating signs;    -   roadside safety systems, e.g. the brake may be connected in a        system; and    -   to provide crash attenuation through the dissipation of energy        in the brake.

Indeed, the braking mechanism as described herein may be used in anyrotary braking and/or speed limiting system.

FIGS. 1-13 illustrate embodiments or portions of a line dispensingdevice 100. The line dispensing device 100 does not include a clutch andthe braking mechanism is permanently connected to and rotates inresponse to all retraction and extension of the line 114. As illustratedin FIG. 1, the line dispensing device 100 includes a shaft 102, a rotor104, pivotable members 106 (three are shown) attached to the rotor 104,a cradle 110 with attached magnets 108, a coupling transmission 112, aline 114, a retracting mechanism 116, and two housing panels 118. In oneembodiment, the line dispensing device 100 is an auto-belay device forallowing a climber to climb and safely be lowered when hanging on theline 114. In the embodiment shown, the line dispensing device 100further includes a biasing device 120, a biasing device attachment 122,an isolation insert 125, a central plate 130, a handle 134, a cradledrum 136, a cradle plate 138, a mechanical connection 154, a nozzle 146,a retracting mechanism drum 141, a retracting mechanism base plate 142,a retracting mechanism inner drum plate 144, a connecting mechanism 148,a guide roller 150, and a line attachment site 152.

When assembled, the outside of the line dispensing device 100 of FIG. 1is defined by two housing panels 118 connected to either side of acentral plate 130. Together, these components act as a housing tosurround and protect the internal components of the device 100. In theembodiment shown, each housing panel 118 includes a side component 126and a side plate 128. The side components 126 may be identical as shownto reduce manufacturing costs. The two side components 126 may be heldtogether with one or more bolts 148 as shown, or any other suitableconnecting mechanism 148.

In the device 100 in FIG. 1, each of the two side components 126 isconnected to a side plate 128. The side plate 128 may be considered awear point and designed to be cheap and easily replaceable in order tomaintain the appearance of the device 100 when in prolonged use. Theside plates 128 may be attached to the side component 126 in any way. Inthe embodiment shown, the side plates 128 include clips for attachingthe side plates 128 to the side component 126. The clips may aid inattachment and provide stability to the side plates 128. Preferably, theside plates 128, and indeed all components of the housing and device 100in general, should be positively attached so that noise from vibrationis reduced.

The side plates 128 are particularly advantageous when used inauto-belay systems for climbers. The side plates 128 cover any sharpedges found within the line dispensing device 100. Auto-belay systemsoften rub against or contact climbing walls during use. The side plates128 prevent a line dispensing device 100 from damaging the climbing wallduring such contact.

In the embodiment shown, each housing panel 118 is roughly cylindricaland provided with two prongs that extend from the side. These prongssurround and direct the eyes of a user to a central mounting aperture inthe mounting point 132 of the central plate 130. This is desired inorder to visually direct the users to the preferred mounting aperture bygiving the impression that the central aperture is the strongestattachment point.

In the embodiment shown, the central plate 130 acts a central frame forthe device 100 from which the other components are hung and throughwhich the device 100 is attached to a fixed anchor for use. The centralplate 130, as shown, is a unitary component made of metal or othersuitably strong material and includes an integral mounting point 132that has three separate apertures, any one (or more) of which can beused as the attachment point for the device 100. It should be noted thatthis is just one method for providing an attachment point and, inalternative embodiments, the mounting point 132 may be a portion of ahousing panel 118 or may be separate, removable component that can beattached to the device 100.

In the embodiment shown, the mounting point 132 includes a main mountingaperture 131 (flanked by the two prongs of each side component 126), analternate mounting aperture 133, and a handle 134 on either side of themain mounting aperture 131. Depending on the needs of the user, anynumber, shape and configuration of apertures can provided. However, themounting point 132 as shown in FIG. 1 has several advantages. Themultiple mounting apertures allows for a back-up or secondary line to berun through the alternative mounting aperture to secure the linedispensing device 100 if the primary mounting fails. The multipleapertures allow for equi-tensioned multiple point mounting as ispreferred in some climbing gyms. Because the handle 134 is offset fromthe mounting aperture, it provides a means for holding the linedispensing device 100 during mounting that is separate from the mountingaperture. This is a benefit over other devices that provide only onemounting aperture that also serves as a handle which require theoperator mounting the device 100 to let go of the handle when mountingthe device 100.

As discussed above, in one embodiment, the line dispensing device 100includes a central plate 130. The central plate 130 is a hollowcomponent located at or near the center of the line dispensing device100. As discussed above, the central plate 130 may include the mountingpoint 132. In one embodiment, the shaft 102 extends through the centralplate 130. The shaft 102 may further extend through the center of aspool of line 114.

The shaft 102 provides the axis of rotation about with the line 114 iscoiled and uncoiled during use. In the embodiment shown, the shaft 102is fixed and extends through the rotor 104, the cradle 110, and theretraction mechanism 116. The rotor 104 and the cradle 110 rotate aroundthe shaft 102. In the embodiment shown, a portion of the retractionmechanism 116 also moves around the shaft 102. In an alternativeembodiment, not shown, the rotor 104, the cradle 110, and/or theretraction mechanism 116 do not rotate around the shaft 102, but insteadrotate around an axis parallel to the shaft 102.

In the embodiment shown, each end of the shaft 102 is mounted to ahousing panel 118. Furthermore, each end of the shaft 102 is anchored toits respective housing panel 118 using a flexible isolation insert 125that fits into an aperture provided in the side component 126 (or, moreprecisely in the case of the embodiment illustrated in FIG. 1, betweenan oval plate 124 and the side component 126). The isolation insert 125may be made of rubber or any other suitable material and is preferablyflexible. The isolation insert 125 reduces noise produced by the linedispensing device 100 and dampens vibrations during use.

In one embodiment, the isolation insert 125 fastens to an oval plate124. The oval plate 124 feeds into the housing panel 118 and is retainedin the interior of the device 100 by a flange. The attachment of theisolation insert 125 with an oval plate 124 and a flange provide asafety feature. In this configuration, even if the isolation insert 125fails, the shaft 102 will remain trapped within the housing panel 118 aseven without the isolation insert 125 the oval plate 124 can not beremoved from the device 100 without first removing the housing panel118. This is important in that the isolation insert 125 is anticipatedto degrade over time as it flexes and wears in response to thevibrations created during use. Operators of the device 100 will bealerted to wear of the isolation insert 125 by an increase in noise fromthe device 100, giving an audible cue to the operator to service thedevice 100.

In the embodiment shown, the line dispensing device 100 includes twoidentical isolation inserts 125 mounted in the same position on oppositesides of the housing panel 118. The utilization of identical isolationinserts 125 may allow for cost effective manufacturing of thiscomponent. Furthermore, in the embodiment shown, the isolation insert125 anchors a portion of the coupling transmission 112 as thetransmission is also attached to the oval plate 124 through an idleshaft 113 connected to an idle gear 111 of the coupling transmission112, as illustrated in FIG. 1 (see also FIG. 12). In the embodimentshown, only one isolation insert 125 will anchor the couplingtransmission 112; however, the other isolation inserts (not shown), maybe provided at different locations within the device 100 in order tofurther dampen vibration, reduce noise and reduce wear.

Turning now to the braking mechanism of the device 100, as discussedabove the braking mechanism includes a rotor 104 that spins within achamber created by the cradle drum 136 and the cradle plate 138. Therotor 104 includes pivotable members 106 (in the embodiment illustratedthere are three pivotable members 106, although any number of memberssuch as one, two, four, five, six etc. and any suitable member shape andconfiguration may be used). In the embodiment shown each pivotablemember 106 is pivotally attached to the rotor 104. A line 114 isdirectly or indirectly coupled to the rotor 104 and, thus, the pivotablemembers 106. Accordingly, as the line 114 extends or retracts, the rotor104 and the pivotable members 106 rotate about the axis created by theshaft 102. As the rotor 104 rotates, centripetal force pushes on thepivotable members 106. The amount of centripetal force acting upon thepivotable members 106 increases as the speed of the rotation of therotor 104 increases. The pivotable members 106 are configured to pivotand/or extend upon rotation in either direction. In an embodiment, withmore than one pivotable member 106, the pivotable members 106 areconfigured to nest together when the rotor 104 is stationary, asillustrated in FIGS. 9 and 10. In another embodiment, the outer edges ofthe pivotable members 106 are arc-shaped. The nesting configuration forthe pivotable members 106 allows the pivotable members 106 to pivot andextend outward when the rotor 104 is rotating in either direction.

The rotor 104 is positioned within the cradle 110. In one embodiment,the cradle 110 is configured to position and hold the magnets 108 andthe rotor 104 is a conductive member. In an alternative embodiment, notshown, the cradle 110 is a conductive member and the rotor 104 isconfigured to hold magnets 108. The magnets 108 are positioned to applya magnetic field extending at least partially orthogonal to a plane ofrotation of the conductive member. In either embodiment, the componentholding the magnet 108 are made of a material that provides for low orno resistance to the magnetic field created by the magnets 108.Accordingly, depending upon the configuration, the conductive member maybe the pivotable members 106 or the cradle 110. As the pivotable members106 of the rotor 104 expand, a larger portion of the conductive memberenters the magnetic field. This interaction with the magnetic field actsas a braking mechanism causing the cradle 110 and the rotor 104 to slow,which causes the coupled line 114 to slow as well.

In one embodiment, the pivotable members 106 are retracted with abiasing device 120. The biasing device 120 may continuously apply abiasing force toward a nested position of the pivotable members 106. Thebiasing device 120 may be any suitable retracting device, such as aspring or elastic band. In another embodiment, the biasing device 120may be attached to the pivotable members 106 with a biasing deviceattachment 122, as illustrated in FIGS. 9 and 10. In one embodiment, thebiasing device 120 includes a calibration device (not shown), whichallows the amount of biasing force applied by the biasing device 120 tobe adjusted as desired. Accordingly, the biasing device 120 isadjustable to provide for a desirable braking force based on the end useof the line dispensing device 100. The biasing device 120 increases theamount of rotational/centripetal force necessary to expand and/or pivotthe pivotable members 106.

In one embodiment, the cradle 110 includes a cradle drum 136 and cradleplate 138. In one embodiment, the magnets 108 are on only one side ofthe rotor 104. In an alternative embodiment, the magnets 108 include atleast two magnets 108 that are positioned on two sides of the rotor 104.In one embodiment, the at least two magnets 108 are attached to thecradle drum 136 and the cradle plate 138. In an alternative embodimentnot shown, the magnets 108 include a plurality of magnets 108. Theplurality of magnets 108 may be positioned on one or two sides of thepivotable member 106 and/or rotor 104. In an embodiment, the magnets 108on the cradle drum 136 are symmetrical with or positioned identically tothe magnets 108 on the cradle plate 138.

In one embodiment, when the rotor 104 is stationary, the rotor 104 isalready partially within the magnetic field of the magnets 108 on thecradle 110. This configuration applies a constant braking force to theline 114 during line retraction. Accordingly, the braking mechanism isalways engaged regardless of whether the line 114 is being retracted orfed out in this embodiment. Furthermore, in an embodiment the constantbraking force may be adjusted to allow for relatively faster or slowerrates of retraction depending on the needs of the operator.

As illustrated in FIGS. 1 and 8, the cradle 110 is coupled to thecoupling transmission 112 and the line 114 at the line attachment site152. In the shown embodiment, the cradle plate 138 of the cradle 110interacts with the coupling transmission 112. The cradle plate 138includes teeth that interact with the coupling transmission 112.Further, as shown in FIG. 8, the cradle drum 136 includes a centerportion that extends towards the retraction mechanism 116. The extensionof the cradle drum 136 is attached to the retracting mechanism drum 140via a connecting mechanism 148, such as a screw or bolt system. Theextension of the cradle drum 136 further includes the line attachmentsite 152. In one embodiment, the line attachment site 152 is a bar orpin. In the embodiment illustrated, the cradle 110 and the retractionmechanism drum plate 141 are fixed together and form a spool portionbetween them to which the line 114 is attached and around which the line114 is wound.

As shown in FIGS. 1 and 3, the coupling transmission 112 couples therotor 104 to the cradle 110 and, thus, the line 114 since the spool andthe cradle 110 are directly connected. In the embodiment shown, theextension of the line 114 causes the cradle 110 to rotate in a firstdirection. The retraction of the line 114 by the retraction mechanism116 causes the cradle 110 to rotate in a second opposite direction.Accordingly, the rotational speed of spool around which the line 114 iswound and the rotational speed of the cradle 110 will be the same. Therotation of the cradle 110 interacts with the coupling transmission 112and causes the coupling transmission 112 to move. In one embodiment, themovement of the coupling transmission 112 causes the rotor 104 to rotatein the opposite direction of the cradle 110. In an alternativeembodiment, the movement of the coupling transmission 112 causes therotor 104 to rotate in the same direction as the cradle 110 but at adifferent speed.

In one embodiment, the coupling transmission 112 is a mechanical orfluid gear transmission system. In another embodiment, the couplingtransmission 112 is a mechanical or fluid chain drive or frictioncoupling transmission system or any other such transmission as is wellknown to those skilled in the art. In an embodiment with a geartransmission, the gear transmission 112 may have a second idle geardrive system 111 that is mounted with an idler shaft 113 parallel toshaft 102. In this embodiment, idler gear 111 interacts with teethlocated on the rotor 104. In an alternative embodiment, idler gear 111interacts with teeth located on the cradle 110. The couplingtransmission 112 may rotate the rotor 104 at a rate that is apredetermined ratio from the speed of rotation of the cradle 110. Thisratio may be set based on the intended use of the line dispensing device100.

The rotor 104, magnets 108, cradle 110, and coupling transmission 112interact to form an eddy-current braking mechanism. The eddy-currentbraking mechanism does not utilize a clutch. Further, the eddy-currentbraking mechanism as described herein may be configured such that thespeed of extension of the line 114 is constant over a range of appliedtorques (the “operating range”), the applied torque being the forceapplied to the rotor 104 or cradle 110 causing it to rotate. In oneembodiment, the eddy-current braking mechanism is utilized in anauto-belay line dispensing device. In this embodiment, the torqueoperating range covers the torque of objects attached to the line 114weighing from about 20 to about 330 pounds (about 10 to 150 kilograms).

This constant speed of rotation, as illustrated in FIGS. 18-19, mayarise due to any increase in the applied torque (in the operating range)being balanced by an equal and opposite increase in the braking torquearising from the induced eddy current as the conductor (i.e. thepivotable members 106 or cradle 110 depending upon the configuration)intersects more of the magnet field.

Thus, when the rotor initially begins to rotate, the speed of rotationof the eddy-current braking mechanism increases substantially linearlywith the applied torque as illustrated in FIGS. 18-19. This situationcontinues until the electrical conductor, which is coupled to the rotorto rotate with it, enters the applied magnetic field of the magnet.Movement of the conductor through the magnetic field induces eddycurrents in the conductor which oppose the motion through the magneticfield, thus providing a braking force on the motion of the conductor.The magnitude of the braking force depends on a number of factors,including the degree to which the conductor intersects the magneticfield and the strength of the field.

As shown in the progression from FIG. 16 a to FIG. 16 c, upon atangential force F_(App) being applied to the rotor 104 (e.g. from aclimber descending), the rotor 104 will rotate and the arms 106 willpivot about pivot points 8. As the applied force F_(App) accelerates therotor 104, the arms 106 will move into, and intersect the appliedmagnetic field 6. Any movement of the arms 106 through the appliedmagnetic field 6 (e.g. when rotating) induces eddy-currents in the arms106 which in turn generate reactive magnetic fields opposing the appliedmagnetic field 6. FIG. 17 shows the magnets 108 positioned either sideof the plane of rotation of the arms 106.

It will be appreciated that the force diagrams of FIGS. 16 a-16 c do notshow an accurate detailed analysis of the many and varied dynamic forcesacting on the arm 160 and thus the forces shown are simplistic andindicative only. The force diagrams 16 a-16 c, are provided to show asimplified example of the primary forces acting on the arm. Each diagram16 a-16 c includes a box with the main forces added to show theapproximate net force at the center of mass 9. It should be appreciatedthat these forces are indicative only and the force lines may not be ofaccurate length or direction.

FIG. 5 a shows a force diagram of the eddy-current braking mechanism 1in an initial ‘start-up’ stage where there is only a tangentiallyapplied force F_(App) and the spring 120 is not extended. As this forceF_(App) is applied tangentially to the rotor, a torque T_(A) applied tothe rotor and it will accelerate from rest. Components ( F_(App) (8) andF _(App) (13)) of this force F_(App) are respectively applied to the arm106 via the pivot point 8 and spring connection 122 a (also labeled as13).

FIG. 16 b shows the applied force F_(App) accelerating the rotor 104 andattached arm 106. The arm 106 is pivoted at a greater angulardisplacement than that shown in FIG. 16 a and now intersects themagnetic field 6. The rotor 104 and arm 106 have gained angular velocityabout the rotor axis X and the arm 106 is accelerated towards the rotoraxis X under centripetal acceleration. The mass centroid 9 applies acentrifugal force F_(cp) to the arm 106.

In addition to the rotary forces, the eddy-current braking forceF_(EDDY) is also applied as the arm 160 is moving through the magneticfield.

The resultant force F_(R) of the forces F_(App) (K), F_(App)(13),F_(cp), and F_(EDDY) act on the mass centroid 8 to accelerate the arm106 further outward from the rotor axis X.

The resulting anticlockwise rotation of the arm 3 about the pivot 8increases the distance between connections 112 a and connection 122 bthereby extending the spring 120. The extension of the spring 120increases the spring bias F_(s) and correspondently increasesF_(App)(13) applied to connection 122 a.

The rotor 104 will continue to accelerate and the arm 106 will continueto pivot anticlockwise until the force F_(App)(13) applied by the spring120 on the arm 106 is sufficiently large to balance the forces acting onthe arm such that F₁₁ and M₁₁ reduce to zero. At this point, the brakingtorque T_(β)applied to the rotor through the transfer of F_(mDY) viapivot 8 and connection 122 b equals the applied torque T_(App), theangular acceleration is thus equal to zero and the rotor 104 will rotateat a constant speed. A steady-state equilibrium position is then reachedas shown in FIG. 16 c.

In an eddy-current braking mechanism, as described herein, the strengthof the magnetic field, configuration of the conductor, and the biasingdevice 120, may all be chosen such that an increase in torque applied tothe rotor 104 is balanced by an equal and opposite increase in brakingtorque throughout the required operating range of torque, for a constantspeed of rotation of the rotor 104 throughout the operating range.Accordingly, if the line dispensing device 100 is utilized to lower anobject weighing 25 pounds and an object weighing 305 pounds, the objectswill be lowered at substantially the same speed and/or rate by the linedispensing device 100.

At some applied torque the conductor may intersect the maximum area ofmagnetic field available under the particular embodiment of the brakingmechanism. At this torque the braking force is also at a maximum.Therefore, as the applied torque is increased further, the speed ofrotation will again become substantially linear with respect to theincrease in applied torque.

For example, speed profiles of the eddy current braking system showingthe operating range are shown in FIGS. 18 and 19. As can be seen fromFIGS. 17 and 18, the speed initially increases with applied torque T_(A)until the resultant force F₁₁ acting on the mass centroid acceleratesthe arms 106 outward into the magnetic field 6 and the reactive brakingforce F_(EDDY) is applied. The resultant braking torque T_(B) willincrease and then equal the applied torque T_(App). The speed ofrotation is thereby limited to a constant value as no acceleration canoccur due to the applied torque T_(App) being continually matched by thebraking torque T_(B). Increases in applied torque T_(A) are matched byincreases in braking torque T_(B) until an upper limit is reached wherethe maximum area of magnetic field 6 is intersected and thus themagnetic field reactive force F_(β) generated is proportional to speedonly. After the upper limit, the speed profile is similar to prior artdevices which vary the braking torque T_(s) with speed only.

As discussed above, the pivotable members 106 are pivotally mounted tothe rotor 104. Further, the pivotable members 106 may include a biasingdevice 120. Even though one or both of the pivoting attachment of thepivotable members 106 or the biasing device 120 could mechanically fail,the eddy-current braking system will continue to function. Theeddy-current braking mechanism inherently provides a safety stop in theevent of a failure. For instance, if the biasing device 120 fails, thepivotable members 106 will simply expand with less rotational forcecausing the conductor to enter the magnetic field sooner, which merelycauses the eddy-current mechanism to brake faster and/or sooner.Accordingly, the eddy-current braking mechanism does not contain aclutch and provides inherent safety mechanisms for these potentialmechanical failures within the eddy-current braking.

The retraction mechanism 116 is either always biasing line 114 toretract or is at rest when the line 114 is fully retracted or retractedto an intended stopping or resting position. The force applied by theretraction mechanism 116 must be overcome to extend line 114. In oneembodiment, the retraction mechanism 116 is a spring as illustrated inFIG. 13. The retraction mechanism 116 is attached to the shaft 102 atone end. The retraction mechanism 116 is operatively coupled to the line114. As used herein the term “operatively coupled” to line 114 should beunderstood to mean any direct or indirect connection such that theretraction mechanism 116 moves with the extension or retraction of line114. It should also be appreciated that connection need not bemechanical. As the line 114 extends, the retraction mechanism 116 iscontracted increasing the biasing force applied to the line 114 by theretraction mechanism 116.

In one embodiment, the retraction mechanism 116 is housed in aretracting mechanism drum 140. The drum 140 may include a drum plate141, a base plate 142, and an inner drum plate 144. The drum 140 fullyencloses the retraction mechanism 116. The inner drum plate 144 may belocated adjacent to retraction mechanism 116 within the drum plate 141.The base plate 142 may be located adjacent to the retraction mechanism116 opposite the inner drum plate 144 and outside of the drum plate 141.In one embodiment, the inner drum plate 144 and base plate 142 preventthe retraction mechanism 116 from moving axially along the shaft 102. Inthe embodiment shown, the inner drum plate 144 and base plate 142 may bemounted to the drum plate 141 by any suitable connection mechanism foruse in a line dispensing device 100. In one embodiment, clips areutilized to further stabilize and decrease the noise between the drumplate 141, the inner drum plate 144, and the base plate 142.

In one embodiment, one side of the drum plate 141 is attached to aportion of the cradle 110 via a connecting mechanism 148. As discussedabove, the drum plate 141 may be attached to a portion that extends fromthe cradle drum 136 as illustrated in FIG. 8. In this embodiment, theretraction mechanism 116 is attached to the drum plate 141. Accordingly,the drum 140 rotates and causes the retraction mechanism 116 to contractas the cradle 110 rotates when the line 114 is extended. Further, inthis embodiment, the drum 140 rotates in the opposite direction when thetorque on the line 114 is less than the biasing force applied by theretraction mechanism 116. Accordingly, the rotation of the drum 140 inthis direction causes the line 114 to retract.

While the rotation of the cradle 110 in the opposite direction does notallow the pivotable member 106 of the rotor 104 to expand or pivot, therotation of the rotor 104 still intensifies the interaction of theconductive member with the magnetic field of the magnets 108 andincreases the braking force applied to the line 114 during retraction.This interaction allows an empty, fully extended line 114 to be releasedfor retraction without the risk of causing any damage to the body of theline dispensing device 100. The braking mechanism causes the line 114 toretract at a slower speed preventing the line 114 from whipping up andpotentially damaging the line dispensing device 100, surrounding objectsand/or people during the retraction of the line 114.

As discussed above, the line 114 is attached to the cradle 110 via aline attachment site 152. In one embodiment, the line 114 is a type ofwebbing. The line 114 may be one continuous piece or may be divided intoa plurality of pieces. In one embodiment, the line 114 includes astarter portion that anchors the remaining line or primary portion tothe cradle 110. The starter portion contains a means for connecting theline 114 to the cradle 110. In one embodiment, the line 114 is attachedto the cradle 110 via a pin and loop mechanism. The starter portion isconnected to the primary portion with a mechanical connection 154. Inanother embodiment, the mechanical connection 154 is a shackle. Thestarter portion of the line 114 allows the primary portion of the line114 to be replaced at the mechanical connection 154 without having todisassemble the line dispensing device 100. In one embodiment, the line114 winds around the cradle 110 as shown in FIGS. 6 and 7.

As shown in FIGS. 1 and 6, the line 114 utilizes a guide roller 150before exiting the device 100. The guide roller 150 is attached to thehousing panels 118. The guide roller 150 positions the line 114 to exitthe housing panels 118. Further, the guide roller 150 provides forsmoother extension and retraction of line 114.

In an embodiment, the line 114 moves through a nozzle 146 attached tothe housing panels 118. In an embodiment, the nozzle 146 is removablefrom the housing panels 118 and provides an opening in the device 100for the line 114 to extend and retract through. In one embodiment, thenozzle 146 is made of a plurality of parts. In another embodiment, thenozzle 146 includes two identical pieces that can be combined with au-shaped pin, as illustrated in FIG. 1. In yet another embodiment, thenozzle 146 snap fits into the housing panels 118. In another embodiment,the nozzle 146 is slid into the housing panels 118 and locked in placewith a u-shaped pin as illustrated in FIGS. 4 and 5. The nozzle 146 maybe attached to the housing panels 118 in any suitable manner forallowing the nozzle 146 to be removed and reinstalled into the housingpanels 118. In a further embodiment, a majority of the nozzle 146 islocated exterior to the housing panels 118.

As a safety feature, in one embodiment, the nozzle 146 is designed tobear a load beyond the capacity of the line dispensing device 100.Accordingly, the nozzle 146 is suitable for holding the line 114 and theweight of anything attached to the line 114 in the event the starterportion of line 114 detaches from the cradle 110 and is held up solelyby the nozzle 146. In the embodiment shown, the line 114 has amechanical connection 154 between the starter portion of line 114 andthe primary portion of line 114 that is too large to exit through thenozzle 146 and is retained by nozzle 146 in the event of a line 114failure. However, if the nozzle 146 is removed from the housing panels118, the mechanical connection 154 is small enough to exit the housingpanels 118 to allow access to the mechanical connection 154 forreplacement of the main portion of the line 114. In an alternativeembodiment, a stop portion (not shown) that is not the mechanicalconnection 154 may be provided at any location in the line 114specifically to prevent further extension of the line 114.

During use, the line 114 of the line dispensing device 100 often rubsagainst the nozzle 146. In certain circumstances, this contact weakensthe line 114 or even causes the line 114 to fail. Accordingly, in oneembodiment, the nozzle 146 is made of a polymer specifically selectedfor its wear properties vis-à-vis the line material. In an embodiment,the polymer is a polyethylene-based polymer. In another embodiment, thepolymer is polyoxymethylene. The polyethylene-based polymer orpolyoxymethylene nozzle becomes worn from contact between the nozzle 146and the line 114; however, it has been determined through testing thatthese polymers cause very little, if any, wear to the line 114. Thus, inan embodiment, it is preferable that at least the surface of the nozzle146 that contacts the line 114, if not all of the nozzle 146, be made ofa polyethylene-based polymer or polyoxymethylene. Other polymer speciesor materials that reduce wear on the line 114 used may be substituted.If the nozzle 146 becomes damaged, the nozzle 146 can be easily removedand replaced.

FIG. 14 illustrates an embodiment of a method for dispensing andretracting a line of a line dispensing device 1400. As illustrated inFIG. 2, method 1400 provides a line for extension and retraction 1402.In one embodiment, the line is webbing. The line may be one continuouspiece or may be divided into a plurality of pieces. In one embodiment,the line includes a starter portion that anchors the remaining line orprimary portion to the line dispensing device. The starter portion isconnected to the primary portion of line with a mechanical connection.In another embodiment, the mechanical connection is a shackle. Thestarter portion of the line allows the primary portion of the line to bereplaced at the mechanical connection without having to disassemble theline dispensing device.

Further, method 1400 applies a retraction force to the line with aretracting mechanism 1404. In one embodiment, the retracting mechanismis a spring. The retracting mechanism may be any suitable device forretracting a line in a line dispensing device. In one embodiment, theretracting mechanism is always active or is always applying a retractionforce to the line. Accordingly, for the line to extend, the line mustovercome this retraction force. The retraction mechanism is anchored tothe line dispensing device and operatively coupled to the line.

Method 1400 applies a braking force to the line providing asubstantially constant speed for extension over a range of appliedtorques 1406, as illustrated in FIGS. 18-19. The braking force isprovided by balancing an increase in an applied torque with an equal andopposite increase in a braking torque arising from an inducededdy-current from conductive members intersecting a larger portion of amagnetic field. In one embodiment, the range of applied torques coversobjects attached to the line weighing from about 20 to 330 pounds.

In one embodiment, method 1400 further applies a braking force to theline for retraction with the intersection of the conductive members andthe magnetic field from an induced eddy-current. The braking forcereduces retraction speed of the line enough to allow a fully extendedline with nothing attached to the line to “cleanly retract”. As usedherein, the phrase “cleanly retract” refers to retraction that is slowenough to allow a fully extended line with nothing attached to the lineto fully retract without damaging the line dispensing device orexcessive whipping, which could injure nearby objects or persons.

Embodiments of the line dispensing devices as described above areparticularly adapted for certain uses in which safe and controlledextension and retraction of a line is necessary, such as for use inchallenge courses, adventure courses, races, training and evacuation.Current auto-belay safety devices are not suitable for such uses becausethey are either designed for single use (e.g., to protect a singleuncontrolled fall) or, if they are allowed to retract without a load(e.g., a user releases the line allowing the device to retract the linewith no load), they do so in an uncontrolled and dangerous fashion at avery high speed often resulting in damage to the device or the line.

In embodiments of the devices described herein, the braking mechanismcan be designed to apply a first amount of braking when under load sothat loads are lowered at a first velocity and apply a second amount ofbraking when retracting an unloaded line with the retraction mechanism.This allows the line dispensing devices described herein to be usedsafely and repeatedly as a lowering device.

A challenge course is a term that refers to obstacle-type coursesdesigned to challenge a person or team, and are sometimes referred to asa “ropes course”. These are popular in the United States for teambuilding events and they often include obstacles that involve one ormore participants to perform actions some height above the ground.Currently, such courses use a human belayer to protect the participantat risk in case the participant falls from the obstacle. One use of theline dispensing device is to replace the human belayer with the linedispensing devices. Current auto-belay devices are unsuitable for thisapplication because the cost of replacing or servicing the device aftereach fall would be cost prohibitive. Because the line dispensing devicesdescribed herein can retract safely at a controlled speed due thebraking effect, the human belayer can be replaced with a line dispensingdevice.

An adventure course refers to courses provided for fun and thrill thatoften include things like crossing bridges, ziplines, rappelling orclimbing done at a height above the ground. While participants are notintended to fall, because of the potential risk participants are oftenbelayed by a human while at unsafe heights. Again, because of theability of some embodiments of the line dispensing devices to retractsafely and repeatedly when not loaded, these embodiments are suitablefor replacing the human belayer.

Likewise, training activities that involve performing actions at heightsare another example of an activities in which embodiments describedherein may be used to replace human belayers. Such activities couldinclude military, police, search and rescue and fire department trainingactivities. These activities could include rappelling or jumping fromfixed platforms (e.g., down the side of buildings) or from movingplatforms (e.g., helicopters, gondolas, decks of ships). In such uses,the line dispensing device could be the means of lowering theparticipants (e.g., to protect jumpers) or be a back-up safety device(e.g., to protect a person on rappel).

Another activity for which the embodiments described herein areparticularly suited are contests that include descending from a height.Because the line retraction speed is fixed and safe, the line dispensingdevice can be used to protect contestants in adventure races involvingrappelling and jumping from heights, or any other activity at a height.As the retraction speed will be the same for all contestants, thisvariable is removed from the contest.

Yet another use for the line dispensing devices described herein is asan evacuation aid in situations where multiple people may have to beevacuated from a height (e.g., oil platform, scaffolding, window washingplatform, etc.) but where it is not feasible to have an auto-belay foreach person. For example, the upper platform around the crown block ofan oil derrick could be provided with an embodiment of a line-dispensingdevice having enough fire-resistant line to reach the ground. Thisdevice could then be used as the escape mechanism instead of or inaddition to the Geronimo line.

The induced eddy-current braking may be performed by the eddy-currentbraking mechanism as described herein and/or in PCT Application No.PCT/NZ2010/000011, filed Jan. 29, 2010, and entitled, “Improvements inand relating to braking mechanisms”, which is hereby incorporated in itsentirety herein, by reference.

It will be clear that the systems and methods described herein are welladapted to attain the ends and advantages mentioned as well as thoseinherent therein. Those skilled in the art will recognize that themethods and systems within this specification may be implemented in manymanners and as such are not to be limited by the foregoing exemplifiedembodiments and examples. In this regard, any number of the features ofthe different embodiments described herein may be combined into onesingle embodiment and alternate embodiments having fewer than or morethan all of the features herein described are possible.

While various embodiments have been described for purposes of thisdisclosure, various changes and modifications may be made which are wellwithin the scope of the disclosure. For example, the materials utilizedmay be modified and the housing may be made in any suitable shape basedon the desired end use of the line dispensing device. Numerous otherchanges may be made which will readily suggest themselves to thoseskilled in the art and which are encompassed in the spirit of thedisclosure.

What is claimed is:
 1. A method for dispensing and retracting a line ofa dispensing device, the method comprising: rotating a cradle around ashaft in a first direction in response to a retraction force applied viaa retracting mechanism that is attached to the cradle at a first end andattached to the shaft at a second end of the retracting mechanism;rotating at least one magnet attached to the cradle around the shaft inthe first direction when the cradle rotates in the first direction;rotating the cradle around the shaft in a second direction in responseto an extension force on the line sufficient to overcome the retractionforce applied via the retracting mechanism; rotating the at least onemagnet attached to the cradle around the shaft in the second directionwhen the cradle rotates in the second direction; rotating a rotor,located within the cradle and coupled to the cradle via a transmissionsystem, around the shaft in response to the cradle rotating in the oneof the first and second directions, wherein the rotor is configured torotate in response to the cradle rotating in the first direction and therotor is configured to rotate in response to the cradle rotating in thesecond direction, the rotor including a center component and at leastone pivotable member movably attached to the center component; pivotingthe at least one pivotable member away from the center component andinto a portion of a magnetic field of the at least one magnet, theportion of the magnetic field extending at least partially orthogonal toa plane of rotation of the at least one pivotable member, the at leastone pivotable member extending into a larger amount of the portion ofthe magnetic field as a direct result of increasing centrifugal forcecaused by the rotating of the rotor around the shaft; generating africtionless braking force from an induced eddy-current created by theat least one pivotable member intersecting the portion of the magneticfield to control a rotation speed of the cradle; retracting the lineattached to the cradle when the cradle rotates in the first direction ata substantially constant rate over a range of varying applied retractingforces based on the control of the rotation speed of the cradle; andextending the line attached to the cradle when the cradle rotates in thesecond direction at a substantially constant rate over a range ofvarying applied extending forces based on the control of the rotationspeed of the cradle.
 2. The method of claim 1, wherein the frictionlessbraking force reduces refraction speed of the line enough to allow afully extended line with nothing attached to the line to cleanlyretract.
 3. The method of claim 1, wherein the range of varying appliedextending forces on the line covers objects attached to the lineweighing from about 20 to about 330 pounds.
 4. The method of claim 1,wherein the frictionless braking force is tuned by at least one of thefollowing: varying a strength of the magnetic field; varying aconfiguration of the at least one pivotable member; controlling a rateat which the at least one pivotable member enters the magnetic fieldbased on an integration of a biasing mechanism; and controlling anextent to which the at least one pivotable member enters the magneticfield.
 5. The method of claim 1, wherein the retracting mechanism is aspring.
 6. The method of claim 1, wherein the retracting mechanismalways applies the retraction force to the line.
 7. The method of claim1, wherein the at least one pivotable member is operatively coupled tothe line.
 8. The method of claim 1, wherein the magnetic field iscounter-rotating with respect to the at least one pivotable member.